Control slump and moisture in your product by measuring the raw materials

Scale-Tron’s moisture sensor products are a development from past success.  As a result, we can offer you totally new, reliable moisture meters  to meet different applications while standing up to the rough environment of concrete plants.
AquaSense 2280D microwave moisture meter builds on past successes to give you a totally new, reliable moisture sensor that stands up to the rough environment of concrete plants.
With AquaMix microwave mixer moisture sensor and suitable controller, you can control the water dosing to give consistent moisture or slump in the final product.
AquaControl 1540 controls the water dosing in the mixer. Consequently it gives consistent moisture or slump in the final product.
The SONO-VARIO moisture level sensor uses Time Domain Reflectometry to measure the moisture of the material.
Why do we need moisture measurement in the sand bins? What is the effect on the concrete? Why do we still get variations in slump or moisture? What is a mixer water dosing system? What is a slump meter? Answers to these questions and more below.
Can I take a sensor calibrated for sand and use it on other materials? Can I use AquaSense 2280D’s sampling feature for on-the-fly batch correction? Which is the best output choice, 0-10 volts or 4-20 mA? This page answers your Moisture, Frequently Asked Questions and others.

Four moisture meters for different applications

Moisture measurement is an inexact science.  The reason for this is the measurement zone, which is an area of a few square inches.  Compared with the area of a typical feed gate in a bin, with an area of 150 to 350 square inches, it is very small.  Consequently, aggregates falling from one side of the bin or another, with different moisture values, can escape inclusion in the average as the material flows.  Also, different moisture sensor types are best suited to different materials and environments, as detailed below.

You need to do three things to guarantee success:

  • Hold density constant, since all sensors are density sensitive.  You can accomplish this by installing it in a bin and angling the sensing faceplate to slow and compact the material as it flows past.
  • Make the measurement within the flow region, above the feed gate in a bin; not in the side where material does not flow.
  • Average the readings while the material is flowing.  It should hold the average between batches.

You should install your moisture probe in a bin or hopper where the material is compacted.  This gives reliable density and therefore the most accurate moisture measurement.  Also, smaller granule size, compared with the measurement aperture, gives higher accuracy.  See a discussion of the various types of sensor here. We offer three types of sensor for different environments:


AquaSense measures the moisture of sand, aggregates and granular materials

AquaSense 2280D is the best choice for measuring the moisture of sand and granular materials.  Examples are fine aggregates (up to 1/4″ or 6 mm) or similar products that can be compacted inside a bin or hopper.  The material flows across the moisture sensor and it averages the result during the flow period.  This gives a better average than you can get from oven-dry tests.  It can also be used in a ‘ski’ fixture that rides on top of a thick bed of material on a conveyor belt.  As a result, however, this gives reduced accuracy.  AquaSense 2280D is in use daily in concrete plants, sand and aggregate dryers, frac sand dryers, coal, animal feed mills and many food materials.
AquaSense 2280D is the ONLY moisture sensor with a 10 year guarantee!

Chris, the sensors are working great; we periodically do moisture tests to compare and the results are within 0.2% thus far.  Stan Dean,  General Manager, Milepost Manufacturing, Alberta, Canada, May 2018.


AquaMix, for moisture measurement in the mixer, has an extremely hard faceplate that will withstand the wear in the mixer floor

For use in mixers for concrete and similar applications, AquaMix 2270D uses the hardest known material after diamond, Silicon Nitride, for its faceplate.  Due to this, a life of over 10 years is typical in moisture measurement of extreme aggregates such as granite used daily in mixing of concrete.  You install the moisture sensor in the floor of a pan, ribbon or twin-shaft mixer.  A fixture allows you to adjust for the wear of the liner plates.  Both AquaSense 2280D and AquaMix 2270D use the same setup and calibration software.  If you want to mix widely different blends of material (for example lightweight and regular block mixes), you can store up to 10 different sets of calibration values in the sensor.  You can access these through the serial digital connection.


AquaControl controls the moisture in the mixer

If you do not have a batch controller or it does not have mixer moisture software, AquaControl 1540 can control the addition of water, based on readings from the AquaMix 2270D sensor.  It connects to the moisture probe, water valves and meter.  The controller is based on the same combination of PLC and touch screen used in BatchTron models.  Because of this, three different methods are available to measure and add the water, depending on the application:

  • MicroMix, a simple, calibration-free method that does not require a water meter.
  • Fast MicroMix, requires a water meter but improves speed because it predicts the amount of fast pre-water, then adds it.
  • MasterMix, which requires a water meter plus accurate sensor calibration.  As a result, it gives the ultimate speed and accuracy.


The Sono-Varion moisture sensor is mounted under the discharge gate, in the flowing material

For applications requiring the ultimate accuracy, or for aggregate sizes up to 1.25″ (32mm) the Sono-Vario tdr moisture sensor, sold in North America by Mesa Systems Co. is best.  Using Time-Domain Reflectometry (tdr) at radar frequencies gives deep penetration of the material, less sensitivity to density and consequently a better average.  Its measurement accuracy is 0.1% as a result.  It is mounted on a plate under the gate, in the stream of material.  Scale-Tron does not manufacture this item.  It is available for applications that demand the highest moisture measurement accuracy.

Best service in the business” says Greg Roache of Gainey’s Concrete Products. May 2017